The 10 twist of the factory 300 ultra will work with his 200gr but not the 220gr. I'm going to try the 200's in my Ultra. It has a .797 BC and should be a good LR bullet at Ultra velocities.
Preliminary testing with the Lost River bullets has induced me to label them as fouling SOBs. They may be one case where moly is mandatory! It seems the potential might be there but for the money they have to shoot BETTER than conventional bullets and so far they haven't shown this capability. The high BCs are neat but not the final answer anyway. I'll try some more in a different barrel later and see what they do. The thing is, I can achieve better than 1/2 moa with conventional bullets at long range so these would have to be able to beat this by a substantial margin to get me to blow 2 or 3 bucks downrange with every shot! Regards, Bill.
Bill, what bullet and combination have you tried so far? My 300 Ultra doesn't foul like my others do, so it will be interesting to try them out. I figured I'd try 3 boxes of the 200gr to see what they'll do in the Ultra. I'll notice right away if it fouls more than usual. I'll post my results.
I have been trying the 132gr 6.5s in an 8 twist barrel. If I clean well then shoot three shots they will easily go into 3/8". Further shooting opens the group so that 5 shots will be 7/8 and tenshots about 2 1/2 (that's right two and one half)inches. Since this rifle will quite regularly put 10 sierras into 5/8 or less I don't consider this to be performance! Regards, Bill.